A Hybrid Multi-user Interference Cancellation Scheme for Carrier Frequency Offset Compensation in Uplink OFDMA

Users in the uplink of an Orthogonal Frequency Division Multiple Access (OFDMA) system may experience different carrier frequency offset (CFO). This CFO destroy the orthogonality among subcarriers, causing inter-carrier interference and multi-user interference, which degrade the performance of system. Latest time domain schemes called "SIMUIC" and "CAMUIC" have delay in processing, since each consecutive user's CFO's are corrected with successive iteration method. Also frequency domain compensation performs better, but smaller individual CFO values only. In this paper, a hybrid multi-user interference cancellation scheme for OFDMA uplink is proposed. This employ an architecture with multiple OFDMA-demodulators to compensate the multiuser CFO's at the base station. This hybrid scheme, SPIC exploits the advantages of both time domain and frequency domain schemes. Large CFO values of each user is compensated using an efficient time domain scheme. The remaining CFOs are compensated using a Parallel Interference Cancellation in frequency domain and the CFO corrected output of each user is obtained simultaneously. Analytical and numerical evaluations show that proposed scheme achieves a significant performance gain compared to the latest schemes.